Their roof is I-20 East. Their walls are nylon.

More than 300,000 vehicles each day pass over them on I-20 or whir by on the Downtown Connector, largely unaware of the collection of forgotten and miserable people huddled inside tents, hiding in plain sight next to one of the busiest intersections in the Southeast.

As temperatures were set to plummet to single digits, those living in the 30-some tents just south of downtown readied themselves Monday afternoon for a bone-chilling cold not felt in Atlanta for years.

Life in the cluster of tents is a desperate, nomadic existence, said James L. Wise, a weathered 56-year-old who immediately asked a visitor for a cigarette. Wise, an Atlanta native, recently got his yellow, two-man tent from social workers at Grady Hospital after a stay there.

“It was cold here last night,” said Wise, peeking out from the relative warmth of his shelter in the midday sun. “I got a sleeping bag and four covers.”

Wise has been coming to the area on and off for three years, calling it “scat living.”

“The DOT or state police come in here and we have to scat,” he said, complaining that belongings are often tossed into a dump truck and done away with. “Then you have to start all over again.”

A homeless man who would not give his name huddled by a fire across the street from the tent city. Another man sat on a battered folding chair.

“It’s simple survival,” he said. “You do what you can. All trash is burnable.”

Jerry Lewis, a roofer when he works, said the previous night was cold but not unbearable. The overpass keeps the rain off them and the tents slow down the biting wind, especially when they are huddled together.

“The folks out here don’t like going to the (homeless) shelters; they don’t like the rules,” said Lewis, who is awaiting his tax returns so he can get a room.

Anita Beaty, the director of the massive Metro Atlanta Task Force for the Homeless, expects her shelter to take in 1,000 boarders Monday night, almost double the number of an average evening. Her volunteers try to persuade those staying outside to come into the shelter when it gets bitterly cold, but some homeless people remain wary.

“Some are emotionally or mentally fragile and crowds make them nervous,” she said. “Others are afraid they’ll lose their stuff, that it’ll be confiscated or stolen.”

Josh Waller, policy director of the Georgia Department of Transportation, said those staying on state property are trespassing and can be removed by police.

It is evident the tent city has been there for a while. Piles of bagged garbage lean against a concrete barrier awaiting pickup.

Evelyn Thirkield huddled inside a 6-person tent with a friend and 10 blankets. She had on numerous layers of clothing, including two hoods and two pairs of pants. She said an Atlanta cop gave her a blanket the other day.

Thirkield, who is from Atlanta, said the tent occupants “all watch out for each other,” allowing some to go get food or run errands.

“I just got this (tent) Saturday from a shelter,” she said, pausing and laughing. “Just in the nick of time. Before this, I was just out there laying on the naked ground.”

She has a Bible in her tent and was reading it when a reporter visited.

“Jesus made it like this,” she said. “He lived outside.”

She then zipped up her tent and went back to whatever she was doing.